Defensive publication



73 5? a 061 DEFENSIVE PUBLICATION UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice of Apr. 11, 1968, 849 0.G. 1221. Identification is by serial number of the application and the heading indicates the number of pages of specification, including claims, and of sheets of drawing contained in the application as originally filed. The file of this application is available to the public for inspection; reproduction may be purchased for 30 cents per sheet.

Applications published under the Defensive Publication Program have not been examined as to the merits of alleged invention. The Patent Office makes no assertion as to the novelty of the disclosed subject matter.

PUBLISHED FEBRUARY 4:, 1969 616,504 POLYESTERS AND POLYCARBONATES PREPARED FROM CYANO SUBSTITUTED BISPHENOLS Paul Winthrop Morgan, West Chester, Pa, assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Feb. 16, 1967. Published Feb. 4, 1969 Class 260-47 No Drawing. 18 Pages Specification Novel polyesters and copolyesters are prepared from monoand dicyano-substitnted bisphenols wherein each cyano group is attached to a methylene carbon atom bridging the phenolic rings. Novel polycarbonates and copolycarbonates prepared from dicyano-substituted bisphenols of the type described above. High melting fibers and films having good thermal stability are prepared from these polymers. 

